Meterolgy ( chapter 8 > required skills and knowledge )

Unsaturated adiabatic lapse rate ( dry adiabatic ) is

3 degrees c / 1000ft or 1 degrees c / 100m

Saturated adiabatic lapse rate is

1.8 degrees c / 1000ft or 0.6 degrees c / 100m

Environmental lapse rate ( ELR ) is

1. 2 degrees c / 1000ft

2. Is the temperature profile of the atmosphere

3. Greater at which temp decrease with height the, the higher the ELR

If the ELR is greater than both DALR and SALR then the atmosphere is

Absolutely unstable

If the ELR is less than both DALR and SALR then the atmosphere is

Absolutely stable

If the ELR lies between the DALR and SALR then the atmosphere is

Conditionally stable

Static stability is

Depends on the environmental lapse rate ( ELR ) high is highly variable, especially in the lower atmosphere

Warm saturated air …

Air that cools and warms at a much slower rate

Cold saturated air …

Air that cools and warms at a much faster rate

As unsaturated air rises, what increases?

Relative humidity

As unsaturated air descends, what decreases?

Relative humidity

Saturated air that is forced to rise causes

1. Condensation

2. Latent heat is released to the air so it cools off at a much slower rate than unsaturated

Saturated air that is forced to descend causes

1. Evaporation

2. Latent heat is absorbed from the air so it warms much more slowly than unsaturated air

Stable / absolute stability means

1. That any rising air cools faster than the environment and therefore becomes colder than the environment.

2. This causes the air to sink back down

3. If forced to descend the air warms faster and then rises back up

Unstable / absolute instability means

1. That any rising air cools slower than the environment and therefore becomes warmer than the environment

2. At any given altitude it continues to rise

Conditionally stability means

1. Is determined by whether the air is saturated or not.

2. If saturated, then the air is unstable

3. If unsaturated ( dry ) then the air is stable

Warm air advected over a cooler surface increases …

Stability

Cold air advected over a warmer surface increases

1. Instability

2. Or decreases stability

Inversions represent

1. A situation of absolute stability

2. Strongly resist vertical motion